Changing dietary intake to focus on low carbohydrate and high fat foods could be prescribed as therapy for serious mental health disorders.

A new clinical trial by James Cook University will investigate how changing the body's primary fuel source affects conditions including schizophrenia and bipolar disorder.

Having made headlines as a favourite for weight loss and bodybuilders, ketone or "keto" therapy involves swapping carbohydrates for fat, neuroscientist Zoltan Sarnyai explains.

"The focus is on foods like eggs, meats, dairy, healthy fats such as avocado, nuts, salmon and low-carb vegetables and fruits, as well as sugar-free drinks," Prof Sarnyai said.

"It restricts highly processed items and unhealthy fats."

The intake of macronutrients typically involves a split of 75 per cent fat, 20 per cent protein and five per cent carbohydrates.

When glucose from carbohydrates is no longer the primary fuel source, the body breaks down fat in the liver to produce ketones for energy.

"The body changes its whole metabolism, from breaking down sugars, which is the sort of default condition, to breaking down fat," Prof Sarnyai said.

Several mental health disorders seem to be related to how effectively the brain uses the typical source of energy - glucose.

If brain cells can't efficiently process glucose, the result is less chemical energy.

"If that does not happen properly, nerve cells cannot talk to each other," Prof Sarnyai says.

"Our thoughts, our emotions and our impulses can be affected."

The latest clinical trial follows experiments done on mice that were injected with a drug which produces schizophrenia like psychosis in humans.

"We applied a metabolic therapy in the form of the ketogenic diet in that model and we were able to normalise the drug induced schizophrenia-like state in these animals," Prof Sarnyai says.

Now about 100 patients with serious mental health conditions will be recruited in the North Queensland area to investigate the efficacy of dietary interventions in serious mental illness.

They will then be monitored over 12-weeks to check how their food intake affects symptoms.

A secondary outcome could be better overall physical health for patients whose medications result in weight gain.

People with schizophrenia typically die younger than the general population, mostly as a result of cardiovascular issues emerging from weight gain, Prof Sarnyai says.

His work, along with that of another four research teams, has been backed by a grant from the US-based Baszucki Brain Research Fund.

Researchers from JCU, Stanford University, University of California San Francisco, Edinburgh University and Ohio State University met in May to form a working group studying the effect of a ketogenic therapy on mental disorders.

Depending on the findings of the JCU study, a larger global trial could follow.